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Stop to plastic water bottles
This project was born to eliminate water bottles, the aim is to reduce the use of plastic. Sometime water in bottle has a very good taste if compared to public tap water, so this project is based on filtering water, eliminating impurities and correcting its taste, then I want a filtered water from my kitchen tap directly. In many cases for this application it is usually used a small one-way tap to add on the sink for filtered water, otherwise new multi-ways taps (up to 5 ways) have been designed for this specific application and for different kind of filters.
One-way tap (left) to add, or multi-ways tap (right) to replace a standard two-ways tap.
I don't want to add other taps and I don't like design of new multi-ways taps, then multi-ways taps are very expensive, in some cases more than the total cost of this project. I want to maintain my standard two ways kitchen tap from which I want to obtain filtered and also sparkling water, so the main target of this project is to obtain filtered water directly from my tap, pressing only one button to change the tap behavior. Mine as all standard taps has two ways (cold + hot water), but if we build a system comprising some 3-port electro-pneumatic valves we can control a multiway system switching between two or more channels. Another target is to control water hardness and alkalinity to provide it to my expresso coffee machine and finally obtain also sparkling water from the tap. (If you are fascinated in water specifications related to coffee taste or coffee machines corrosion you can read the interesting posts provided by Jim Schulman on alt.coffee) First of all it's necessary to do a physico-chemical analysis to our public tap water, in order to identify the correct filtering system and filter type we need, or filters types we need if we have to add more than one, for different kind of impurities that only one filter could not control. In my case after the analysis laboratory results I selected a specific microfiltration type system, with a filter dimension of 0.5 µm. The final water taste is perfect, no flavor is distinguishable, it is confirmed also by double-blind tests I have conducted with some friends using my filtered water among different glasses of water from different marks. In the following figure it is represented the scheme of the developed system:
Excluding the sparkling water block this is the realization and installation of the filtering system block (the cold side of the water tap):
The switching valve for the cold water tap is in the middle of the two filters (µfiltration + ion exchange softener) and the UV block on the bottom. All parts are fixed on a wooden panel, the whole system is 12 cm total thickness, I placed it inside one of the bottom cabinets near the sink, without losing too much space
Then I replaced the 3 port motor valves with 3 port solenoid valves, their working methods and action time are very different.
Motorized valve (left), Solenoid valve (right).
The setting time of the motorized valve is about 10 s, for the solenoid valve the setting time depends on water pressure, but generally is less than 200 ms. The motorized valve is powered only during switching time, this is very good for safety and power consumption, but 10 s are too much to wait for filling a glass of water, then they are necessary two actions on the button (the first to switch-on and then to switch-off the valve). While the solenoid valve remains swiched-on for the total time we need to filter water, so we have to pay attention to the valve power consumption. But its action is instantaneous, so thinking to daily actions and time it is the right choice for this application. Selecting the right valve, changing the button action and adding a digital timer to set the switch-on duration, the final system became perfect for all common daily needs.
Motorized valve replaced by a solenoid valve and a digital timer (top left) is added to the system.
With this system if I need unfiltered water no actions are necessary but only to open water tap, if I need filtered water only one action is necessary: it is to press this button one time
A John Guest rapid lock for direct feed filtered water to my expresso machine (left side). Switching button (right side) controlled by the digital timer. This waterproof inox 316 panel is installed near the sink in my kitchen.
After the button is pressed, if I open cold water on tap I obtain filtered water and if I move the tap on the hot side I obtain sparkling water. I have programmed a fixed time of few tens of seconds (the time to fill a bottle), then the system switch-off automatically, returning to the normal condition (untreated tap water). After 1 year the filtered water consumption is about 1.5 m^3, the filter duration in theory is for 10 m^3, but it is heavily dependent on accumulated impurities quantity, in my case I calculated to replace filters about every 3 years. The calculus coming from the incresing time for filtering a fixed quantity of water after a certain time period. After the realization of this project the plastic waste of my house has been reduced of about 40%.
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